I am in the examples folder trying to run - Electromagnetism in Minkowski spacetime <https://nbviewer.jupyter.org/github/ernestyalumni/Gravite/blob/master/EMsage.ipynb> [ipynb <https://raw.githubusercontent.com/ernestyalumni/Gravite/master/EMsage.ipynb>] (Electromagnetic field 2-form from E and B, Maxwell equations, conserved current, Lorentz force, Poynting vector)
but I get the error AttributeError: 'DiffFormFreeModule_with_category.element_class' object has no attribute 'exterior_der' Here's a MWE M = Manifold(4, 'M', latex_name=r'\mathcal{M}', structure='Lorentzian') BL.<t,x,y,z> = M.chart(r"t x y z") var('E_x E_y E_z') dt, dx, dy, dz = BL.coframe()[:] E = E_x * dx + E_y * dy + E_z * dzE.set_name('E') (E.wedge(BL.coframe()[0])).exterior_der() -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sage-support/2c4f6917-8a75-4514-8f97-27999bb265ean%40googlegroups.com.